Unloading valve



June 28,1949. 3.14. ASHTON `Y 2,474,112

UNLOADING VALVE Filed Nov. 24, 1943 4 2 Sheets-Sheet l j@ i 4 l KV I r l40.

INVENToR. Ef/www MS/fro .BQMMY'MI/ N MATTORNEYJ www y June 28, 1949..113. N. ASHTON 2,474,772

UNLOADING VALVE Filed Nov. 24. 1943 2 Sheets-Sheet 2 f4 17 la k IN V ENTOR. w `*25m/Jaim/l/Zswro/v 8%. M* WMZ f4@ ATJ'UHNEYJ Patented June 19492,414,772 UNLoADING vAnva Benjamin N. Ashton, Kingston, N.

Y., assigner to Electrol Incorporated, Kingston, N. Y., a corporationoi.' Delaware- Application November 24, 1943, Serial No. 511,514

l This invention relates to improvements in pressure control valves forhigh pressure hydraulic systems and relates particularly to unloadingvalves for maintaining the pressure in such hydraulic systems within apredeterminedpressure range.

Valves of the type embodying the present invention are particularlyuseful in hydraulic sys- 2 Claims. (Cl. 137-153) tems which are utilizedfor actuating the retractable `landing gear, wing ilaps, bomb bay `doorsand the like `of airplanes. Such hydraulic systems operate usually .atvery high pressures, that is, between about 500 and 3000 pounds persquare inch. The pressure for the system is usually supplied by a pumpthat is driven by the airplane motor and operates continuously dur` ingthe operation of the motor. Inasmuch as the motor driven pump constantlysupplies liquid under pressure, it is necessary to reoirculate theliquid when the system is idle in order to prevent excessive pressuresfrom being built up in the system and causing damage to the operatingelements and conduits.

Various types of valves have been provided heretofore for controllingthe return of the fluid or recirculation of the fluidin the system. Anexample of such a valve isidisclosed in the Ashton and Kling applicationSerial No. 472,964, led January 20, 1943, now Patent Number 2,397,117,granted March 26, 1946.

The unloader valve disclosed in the Ashton and Kling application SerialNo. 472,964 includes a series of` ball valves or poppet valves which areresponsive to the pressure of the iluid supplied .by

\ the pump and to the back pressure in the system in order to causerecirculation of the iluid when a predetermined back pressure isexceeded and to increase the pressure in the system when it has droppedbelow a predetermined minimum.

Valves of the type disclosed in the Ashton and Kling application arevery satisfactory in use, but they have the disadvantage of beingrelatively complicated and expensive because of the necessity ofmanufacturing the various elements of the valve to extremelyclosetolerances in order to avoid leakage at the high operating pressures. Anobject of the present invention is to provide a simplified form ofunloading valve which y is capable of maintaining the liquid pressure inan hydraulic system within predetermined limits. Another object oi theinvention is to provide a compact, simple and emcient unloading valvewhich is easy and inexpensive to manufacture.

Other objects of the invention will become apparent from the followingdescription of typical forms of valves embodying the present invention.

In accordance with the present invention, an unloading valve is providedincluding a check valve which is opened in response to the pressure ofiluid delivered thereagainst, a spring balanced valve which isresponsive to the pressure of iluid delivered to the system and to backpressure of the iluid in the system which controls another valve forbypassing the uld back to the supply source when thel pressure in thesystem exceeds a predeterminedl maximum.

The main operating valves of the system including the bypassing valveand the check valve, in accordance with the present invention, are soconstructed that they need not be machined to close tolerances, butinstead eect sealing engagement by means of one or more rubber ringsdisposed in grooves either in the valve or valve seat which coact withthe complemental element of the valve in order to prevent leakagebetween the elements. The use of such ring-sealed valves `in the systemgreatly facilitates the production of the entire unloading valve,inasmuch as it does away with expensive machining operations and permitsa more convenient arrangement of the elements of the valve.

For a. better understanding of the present invention, reference may behad to the accompanying drawing, in which:

Figure 1 is an end view of the valve embodying the present invention;

Figure-2 is a side view of a typical form of valve embodying theinvention;

Figure 3 is a view in horizontal cross-section of the valve taken online 3--3 of Figure l; and

Figure 4 is a view in cross-section of the pressure control valve forthe system.

A typical form of valve embodying the present invention includes acasing I Il of generally rectangular or box-like form provided with aninlet II at one end thereof. a return coupling I2 at one side thereofand a coupling I3 to be connected. with the hydraulic system at anotherside thereof. The casing I0 is provided with a bore Il extendingentirely through the casing from one end thereof to the other forming acontinuation of the inlet I I.

As shown in Figure 3, the right-hand portion of the bore I4 is providedwith internal threads I5 permitting the inlet to be coupled with aconduit which is connected with the source of iluid pressure, such as apump (not shown). To the left of the threaded portion of the bore I4 isa vbore section I6 of reduced diameter. The bore asuma i tion I1providing a shoulder Il between the bore `22 which is threaded thereintoand is sealed' by means oi a resilient packing ring 23 receivedl in arecess 22a in the plug 22. A flange 22h on the plug abuts the end oi thecasing I0.

At a right angle to the bore I4 is a second bore 24 which communicateswith the bore I4 through a passage 28 of reduced area, thereby forming ashoulder 2i between the bore 24 and the bore I4. The shoulder 28 formsthe seat for a check valve plug 21 of disc-like formation having a'valvestem 21a that is received in a bushing 22 mounted on a spider 20 at theinner end of the coupling I3. The coupling Hl consists oi a sleevemember provided with external threads Ila which are threaded into athreaded portion oi the casing Il adjacent the lower end oi*` the bore24. The coupling sleeve Il is sealed to the casing by means of aresilient ring gasket Il received in a recess Ila in the casing I' andabove a ange lsb on the coupling sleeve It.

l A spring 21h is interposed between the back ot the check valve plug 21and the spider 29 and normally urges the valve plug against the shoulder20.

The seat portion of the shoulder 26 need not be machined to ailuid=tight engagement with the surface o! the valve plug 21 inasmuch asproper sealing relationship is attained by means of a rubbery ring 3|that is mounted in and is of slightly greater thickness than 'the depth.and

width of an annular groove 26a in the shoulder..

The groove 28a is so disposed that the edge of the valve plug 21 atleast partially overlies the groove-and engages the ring 2|.l

A check valve oi' the type described generally above is disclosed in mycopending application Serial lla-506,948, iiled October 20, 1943. Asdescribed in that application, sealing engagement between the valve plugand the seat is eilected by the pressure of the liquid on the back oi'the The casing wis provided-with a third bore 32 extending parallel orsubstantially parallel to the bre I4 and at a right angle to the boreI3. This bore communicates with the bore 24 through a small passage 33through which liquid can flow when the valve plug v21 is displaced fromthe seat 2B. The bore 32 receives the elements forming the pressureresponsive valve that geotrols the fluid pressure in the hydraulic sys-At the right-hand end of the bore is an annular member i4 provided witha small central passage l dening an annular shoulder 34d that forms aseat for a ball valve 31. As illustrated, the bore I5 may be ilared atits right-hand end in order to permit communication with the passage ll.The ring member 34 may also be provided 'with a peripheral groove 34hfor receiving a rubbery ring ll to effect a seal between the wall of thebore I2 and the ring 24.

Abutting the left-hand surface of the ring 34 is an annular spacerelement 38 which is generally L-shaped in cross-section and is providedwith 'one or more radial passages 39a. The

vspacer member .ll maintains a predetermined spacing between the ringmember I4 and a sleeve 40 which is provided with a centrally locatedport 40a that defines a shoulder forming another valve seat 40h for theball I1. As shown particularly in Figure 4, the diameter of the port 4Iais somewhat larger than the diameter of the passagev in order to controlthe range of pressures in the system, as.l will be described presently.'I'he sleeve 40 is retained against the spacer member 39 by means of anexternally threaded sleeve 4I and a lock sleeve 42,

`both threaded into the threaded portion 32a oi the bore l2.

Escape of fluid outside the sleeve is prevented by means of a rubberyring 42 supported v in a groove 40e in the sleeve 40. The sleeve 40 isfurther provided with an annular groove 40d therein which communicateswith a space outwardly of the spacer member 38 by means oi Ione 4or morelongitudinally extending grooves Within the sleeves 40, 4I and 42 isdisposed a plunger 44 having a reduced end portion 44a that engages theball l1. The plunger 44 is urged to the right, thereby forcing the ball31 against the seat 34a by means of a spring 45 which engages f a flange44h on the plunger and an abutment washer 46 carried by a threadedsleeve 41. .The threaded sleeve 41 is threaded into the threaded portion32a ot the bore 32 and can be adjusted along the bore in order to varythe pressure applied by means oi' the spring 45. The plunger extendsthrough the sleeve 41 and is sealed 35 thereto by meansoi' alubbery ring48 that is disposed behind the washer 46 and in front of an annularilange 41a in the interior of the sleeve 41. e l-`The adjustment sleeve41 is sealed to the casing- I0 by means of a compressible gasket 49ylnterposed between a nut 41h on the member 41 and a shoulder 32e at theleft-hand end of the bore. Inasmuch es the gasket 49 is compressible,.

endwise adjustment of the sleeve 41 to vary the compression oi thespring 45 is possible without loss of sealing engagement.

The groove 40d-in the member 4Q communicates with the left-handV end o!the bore section Ieadjacent the plug 22 by means of a conduit 5 0 sothat iluid passing by the ball 31 can escape into the casing section I8which is the cylinder for a piston disc 5I forming one element ofacontrol valve assembly. The pistonv 5I is conhaving an annular groove58a therein for receiving a rubbery sealing ring 51. When the valve 56is disposed partially within the bore portion Il so that the ring 51 canengage the wall ofthe bore portion I8, sealing engagement is eil'ectedand escape of iluid from the righthand end of the bore I4 into the boreportion I8 is prevented. When the piston 5I is displaced to the right byfluid supplied behind the piston 5I, the valve plug 56 is forced out ofthe bore portion I8, thereby permitting uid to escape directly into thisportion and out through the return passage 12a which intersects the boreportion it between its ends and communicates with the coupling l2.

`passage 35.

`The return passage Ila communicates with a space Il in the bore l2between a wall of the bore 32 and a portion 4lb of reduced thickness onthe sleeve 4|. This reduced portion 4lb is i. provided with one or moreradial passages 4Ic i of the piston and the shoulder 20.

Having described thc structural features of the typical form ofunloading valve embodying the invention, a cycle of operation of thevalve will now be described.

When the valve is connectedin a suitable hydraulic system and fluidunder pressure is supplied to the supply coupling Il and the bore I4,

the check valve plug 21 is displaced so that the fluid can pass to thesystem through the coupling I3. At the same time, fluid passes throughthe passage 3l and comes into contact with the ball 31. As the pumpcontinues to operate and pressure is built `up in the system, a pressurewill be attained in the system which is suiiicient to overcome theaction of the spring 45 which may be of sufficient strength to resist apressure of, for example, 1000 pounds per square inch applied to theportion of the ball 31 exposed through the port 35. When this pressureis exceeded slightly, the ball is displaced from the seat 34a,compressing the spring 45 and forcing the ball against the seat formedby the port 40a. Inasmuch as the port 40a is larger than the diameter ofthe port `35, the effective area of the ball on which the pressure actsis increased and the ball is forced against the seat formed by the port40a with increased pressure tending to retain the ball on the seat. Whenthe ball is so displaced, the fluid can pass through the port 39a alongthe groove 40e, into the channel 40d, along the passage 50, therebyacting upon the piston 5| and displacing the piston, together with thevalve plug 56 to the right. inasmuch as the piston 5| is of greater areathan the plug 56. When the plug 56 is displaced to the right,

fluid can pass directly from the bore I4 into the return bore |2a,thereby reducing the pressure on the upstream side of the check valveplug 21 and permitting this valve to close. 'I'his condition will remainuntil the fluid pressure in the system drops below a. predeterminedminimum which is controlled by the relative sizes of the ports and 40a.For example, these ports may be so related in size that 100 pounds dropin pressure on the system side of the valve may be required to permitthe spring 45 to displace the ball from the seat containing the passagea and causing it to engage the seat containingvthe When this conditionis attained, the piston 5| and the valve plug 56 are then moved to theleft by means of the spring 60,

i forcing the liquid outwardly through the passage 50, the` ports 39a,the port 40a through the sleeve 4i, the port 4|c and through thepassage56 into the return line I2. Direct communication between the inlet I4andthe return line pressureagain displaces the check valve plug 21 andcauses the pressure in the system to build up to the maximumpredetermined pressure before the cycle is repeated.

Unloading valves of the type described above can be adjusted to maintaina desired pressure operating range by varying the compression of thespring and by varying the relative` sizes of the ports 35 and 40a. i

These valves are substantially foolproof inasmuch as close fits betweenthe elements of the return valve and the check valve are not required.Moreover, the various valve elements of the unloading valve can beformed of materials whichA are readily available and without thenecessity of precision machining operations in order to cause them tofunction effectively. For example, the casing can be formed by castingwith the various bores therein formed roughly therein and then machinedto thedesired dil I2a, therefore, is cut off so that the liquid under gmensions. The elements of the check valve and pressure release valve 56need not be machined to close tolerances and can be formed ofsubstantially any desired type of material capable of withstanding thepressure utilized in the system. Thus, the valves embodying the presentinvention can be made of aluminum, magnesium, the strong plastics orsubstantially any other type of sturdy material available, inasmuch aswear on these parts is reduced to a minimum by the use of the rubbersealed valves. Accordingly, it will be understood that valves of thetype embodying the present invention are much less expensive than priortypes of unloading valves and can be manufactured more easily than priortypes of unloading valves. It will be understood, of course, that thesize and shape of the various elements may be varied, depending upon therequirements, and that the structural details of the valve may bemodified considerably without departing from the invention. i

Accordingly, it should be understood that the above-described embodimentof the invention is illustrative and should not be considered aslimiting the scope of the following claims.

I claim:

1. A valve for high pressure hydraulic systems comprising a casinghaving a bore therein, said bore having in end to end alignment a firstbore portion, a second bore portion of smaller diameter than said firstportion, a third bore portion of larger diameter thansaid second boreportion, and a fourth bore portion of larger diameter than said thirdbore portion, said fourth bore portion forming a cylinder, and saidfirst bore portion being adapted to be connected witha source of liquidunder pressure, a liquid return line communicating with said second boreportion, a piston in and slidable axially of said cylinder, a valve plughaving a peripheral groove therein connected to said piston and movabletherewith into and out of said second bore portion, a rubbery ring insaid groove for sealing engagement with said plug and said second boreportion, a member having a peripheral groove therein fixed to and spacedfrom said valve plug and disposed in said third bore portion and arubbery sealing ring in the. last mentioned peripheral groove in sealingrelation to said member and said bore for preventing communicationbetween said second bore portion and said cylinder.

2. A valve comprising a casing having a bore therein, said bore havingin end to end alignment a first bore portion, a second smaller diameterboreportion, a third bore portion having a diameter larger than saidsecond bore portion, a fourth bore portion having a diameter larger thansaid third bore portion, means for connecting said rst bore portion to asource of liquid under `pressure and to an hydraulic system, meansclosing one end of the fourth bore portion to form a cylinder, a pistonin and movable axl-^ ally of said cylinder, means for supplying 'uid tosaid cylinder for moving said piston, a valve plug connected to andmovable with said piston between a position atleast partially in saidsecond bore and a position in said first bore portion, means forming aperipheral groove in said valve plug, a rubbery ring in said groove forsealing engagement with said plug and said smaller bore portion, meansforming a liquid return bore intersecting said second bore portion, anda sealing member having a peripheral rubbery sealing ring connected toand movable with said valve plug disposed in said third bore portion forpreventing directcommunication between said cylinder and said secondbore portion.

BENJAMIN N. ASHTON.

REFERENCES CITED The following references are of record in the ille ofthis patent:

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